In order to adjust predictive chassis systems, such as for example active suspension systems of a motor vehicle that will be travelling on the roadways in the future, the course of the road elevation profile in front of the vehicle is traditionally measured with an environment sensor system and processed to obtain an estimated road elevation profile signal. This road elevation profile signal is provided for a predictive chassis control of a user system, such as for example an active suspension system which calculates from this data a proactive actuation signal for respective actuators of the user system. By taking advantage of this prediction, based on a time advantage obtained in this manner by means of the environmental sensor system, for example the driving comfort can be increased, wherein the actuators are being precisely adjusted to each respective environment that is detected by the environment sensor system.
The road elevation signal is therefore needed for an actuation of the respective predictive controls by means of which the respective wheels of the vehicle are being driven, which means that road elevation signal is required for respective trajectories of the vehicle. Traditionally, the road elevation signal is based on a trajectory that is created by using currently known vehicle motion data, such as for example the steering angle, driving speed or acceleration. If the steering angle is not changed, the trajectory will be applied also in a near time window to the section of the road on which the vehicle is to be traveling.
However, if a respective driver carries out steering movements, the trajectory of the vehicle changes dynamically, so that the road elevation information may no longer be used on the basis of the data obtained from previous time windows, as this data is now outside of the range of the current trajectory. In this case, the deviation between the trajectory prediction and the actual trajectory of the vehicle will be increasing with the increasing distance of the predicted trajectory to the motor vehicle. The result of dynamic steering movements of the driver may be for example that the predicted trajectory will leave a current roadway and therefore it will leave the area of the road actually traveled.
In the German patent application DE 10 2012 015 492 A is disclosed a method for operating a chassis for a motor vehicle, wherein a road elevation profile is determined and associated with respective predetermined categories.
The US-American patent application U.S. 2010/0023211 A1 discloses a control system for a chassis of a vehicle, wherein a sensor measures the roadway ahead and based on the measurement data of the sensor, calculates a variable by means of which the actuators of the chassis are adjusted.
A method for operating an active chassis of a motor vehicle is disclosed in German patent application DE 10 2010 018 902 A1, wherein a road elevation profile signal is analyzed for periodically recurring elevation changes and actuators of the chassis are correspondingly adjusted as required.